Return unique_ptr from language_defn::get_compile_context

This changes language_defn::get_compile_context to return a
unique_ptr.  This makes the ownership transfer clear.

gdb/ChangeLog
2021-02-05  Tom Tromey  <tom@tromey.com>

	* compile/compile-c-support.c (get_compile_context)
	(c_get_compile_context, cplus_get_compile_context): Change return
	type.
	* language.c (language_defn::get_compile_instance): New method.
	* language.h (language_defn::get_compile_instance): Change return
	type.  No longer inline.
	* c-lang.c (c_language::get_compile_instance): Change return type.
	(cplus_language::get_compile_instance): Change return type.
	* c-lang.h (c_get_compile_context, cplus_get_compile_context):
	Change return type.
	* compile/compile.c (compile_to_object): Update.

gdb/ChangeLog

@@ -1,3 +1,17 @@
+2021-02-05  Tom Tromey  <tom@tromey.com>
+
+	* compile/compile-c-support.c (get_compile_context)
+	(c_get_compile_context, cplus_get_compile_context): Change return
+	type.
+	* language.c (language_defn::get_compile_instance): New method.
+	* language.h (language_defn::get_compile_instance): Change return
+	type.  No longer inline.
+	* c-lang.c (c_language::get_compile_instance): Change return type.
+	(cplus_language::get_compile_instance): Change return type.
+	* c-lang.h (c_get_compile_context, cplus_get_compile_context):
+	Change return type.
+	* compile/compile.c (compile_to_object): Update.
+
 2021-02-05  Tom Tromey  <tom@tromey.com>
 
 	* parser-defs.h (write_exp_symbol_reference): Declare.

gdb/c-lang.c

@@ -36,8 +36,7 @@
 #include <ctype.h>
 #include "gdbcore.h"
 #include "gdbarch.h"
-
-class compile_instance;
+#include "compile/compile-internal.h"
 
 /* Given a C string type, STR_TYPE, return the corresponding target
    character set name.  */
@@ -888,7 +887,7 @@ class c_language : public language_defn
   }
 
   /* See language.h.  */
-  compile_instance *get_compile_instance () const override
+  std::unique_ptr<compile_instance> get_compile_instance () const override
   {
     return c_get_compile_context ();
   }
@@ -1021,7 +1020,7 @@ class cplus_language : public language_defn
   }
 
   /* See language.h.  */
-  compile_instance *get_compile_instance () const override
+  std::unique_ptr<compile_instance> get_compile_instance () const override
   {
     return cplus_get_compile_context ();
   }

gdb/c-lang.h

@@ -147,21 +147,19 @@ extern bool c_is_string_type_p (struct type *type);
 
 extern int c_textual_element_type (struct type *, char);
 
-/* Create a new instance of the C compiler and return it.  The new
-   compiler is owned by the caller and must be freed using the destroy
-   method.  This function never returns NULL, but rather throws an
-   exception on failure.  This is suitable for use as the
+/* Create a new instance of the C compiler and return it.  This
+   function never returns NULL, but rather throws an exception on
+   failure.  This is suitable for use as the
    language_defn::get_compile_instance method.  */
 
-extern compile_instance *c_get_compile_context (void);
+extern std::unique_ptr<compile_instance> c_get_compile_context ();
 
-/* Create a new instance of the C++ compiler and return it.  The new
-   compiler is owned by the caller and must be freed using the destroy
-   method.  This function never returns NULL, but rather throws an
-   exception on failure.  This is suitable for use as the
+/* Create a new instance of the C++ compiler and return it.  This
+   function never returns NULL, but rather throws an exception on
+   failure.  This is suitable for use as the
    language_defn::get_compile_instance method.  */
 
-extern compile_instance *cplus_get_compile_context ();
+extern std::unique_ptr<compile_instance> cplus_get_compile_context ();
 
 /* This takes the user-supplied text and returns a new bit of code to
    compile.

gdb/compile/compile-c-support.c

@@ -99,7 +99,7 @@ load_libcompile (const char *fe_libcc, const char *fe_context)
 
 template <typename INSTTYPE, typename FUNCTYPE, typename CTXTYPE,
 	  typename BASE_VERSION_TYPE, typename API_VERSION_TYPE>
-compile_instance *
+std::unique_ptr<compile_instance>
 get_compile_context (const char *fe_libcc, const char *fe_context,
 		     BASE_VERSION_TYPE base_version,
 		     API_VERSION_TYPE api_version)
@@ -118,12 +118,12 @@ get_compile_context (const char *fe_libcc, const char *fe_context,
     error (_("The loaded version of GCC does not support the required version "
 	     "of the API."));
 
-  return new INSTTYPE (context);
+  return std::unique_ptr<compile_instance> (new INSTTYPE (context));
 }
 
 /* A C-language implementation of get_compile_context.  */
 
-compile_instance *
+std::unique_ptr<compile_instance>
 c_get_compile_context ()
 {
   return get_compile_context
@@ -135,7 +135,7 @@ c_get_compile_context ()
 
 /* A C++-language implementation of get_compile_context.  */
 
-compile_instance *
+std::unique_ptr<compile_instance>
 cplus_get_compile_context ()
 {
   return get_compile_context

gdb/compile/compile.c

@@ -649,8 +649,8 @@ compile_to_object (struct command_line *cmd, const char *cmd_string,
   expr_pc = get_frame_address_in_block (get_selected_frame (NULL));
 
   /* Set up instance and context for the compiler.  */
-  std::unique_ptr <compile_instance> compiler
-			(current_language->get_compile_instance ());
+  std::unique_ptr<compile_instance> compiler
+    = current_language->get_compile_instance ();
   if (compiler == nullptr)
     error (_("No compiler support for language %s."),
 	   current_language->name ());

gdb/language.c

@@ -46,6 +46,7 @@
 #include "c-lang.h"
 #include <algorithm>
 #include "gdbarch.h"
+#include "compile/compile-internal.h"
 
 static void set_range_case (void);
 
@@ -704,6 +705,14 @@ language_defn::is_string_type_p (struct type *type) const
   return c_is_string_type_p (type);
 }
 
+/* See language.h.  */
+
+std::unique_ptr<compile_instance>
+language_defn::get_compile_instance () const
+{
+  return {};
+}
+
 /* The default implementation of the get_symbol_name_matcher_inner method
    from the language_defn class.  Matches with strncmp_iw.  */
 

gdb/language.h

@@ -374,18 +374,14 @@ struct language_defn
   symbol_name_matcher_ftype *get_symbol_name_matcher
 	(const lookup_name_info &lookup_name) const;
 
-  /* If this language allows compilation from the gdb command line, then
-     this method will return an instance of struct gcc_context appropriate
-     to the language.  If compilation for this language is generally
-     supported, but something goes wrong then an exception is thrown.  The
-     returned compiler instance is owned by its caller and must be
-     deallocated by the caller.  If compilation is not supported for this
-     language then this method returns NULL.  */
+  /* If this language allows compilation from the gdb command line,
+     then this method will return an instance of struct gcc_context
+     appropriate to the language.  If compilation for this language is
+     generally supported, but something goes wrong then an exception
+     is thrown.  If compilation is not supported for this language
+     then this method returns NULL.  */
 
-  virtual compile_instance *get_compile_instance () const
-  {
-    return nullptr;
-  }
+  virtual std::unique_ptr<compile_instance> get_compile_instance () const;
 
   /* This method must be overridden if 'get_compile_instance' is
      overridden.